Retesting rhymes with:
attesting, contesting, protesting, testing, arresting, attesting, besting, breasting, contesting, cresting, digesting, divesting, ingesting, investing, kesting, molesting, nesting, protesting, reinvesting, requesting, resting, suggesting, testing, vesting, wresting
Retesting sounds like:
ratcheting, readjusting, redacting, redstone's, reductions